Channel Bonding

Hi everybody
I am trying to configure channel bonding with Slackware (kernel 2.2.17),
and a 3com nic (905b) but when I use ifenslave I receive the following
message:
The interface eth0 is up, shutting it down it to enslave it.
SIOCSIFSLAVE: Invalid argument.
I tried ifenslave using the old way:
ifenslave eth1 eth0
and the new way
ifconfig bond0 address netmask xxx.xxx.xxx.xxx broadcast xxx.xxx.xxx.xxx up
ifenslave bond0 eth0
ifenslave bond0 eth1
Please someone can help me?
Thanks for your attention
Ricardo